Field
The present invention relates to a backlight device for irradiating a display panel that displays an image and to a display apparatus comprising the backlight device.
Background Art
In recent years, a display apparatus comprising a liquid crystal panel as an image display part is widespread. Such a display apparatus is so configured that a backlight device is placed at the back side of the liquid crystal panel and the light emitted from the backlight device is modulated by and transmitted through the liquid crystal panel to display an image on the front surface of the liquid crystal panel.
A backlight device is so configured that a light guide plate and a light source are accommodated inside a box-shaped backlight chassis with an opening at its one side. The light guide plate is placed to cover substantially the entire bottom plate of the backlight chassis. The light source is, for example, a light emitting diode (LED) and is fixed to a side plate of the backlight chassis to face a side surface of the light guide plate. A frame body is placed at the open side of the backlight chassis to cover the edges of the open side and the edges of the light guide plate. An optical sheet is held on the frame body at the side opposite to the light guide plate. A display apparatus is so configured that a liquid crystal panel, which is supported by the frame body, is arranged to face the optical sheet. In the display apparatus configured in such a manner, the light emitted from the light source enters the light guide plate at the side surface thereof and progresses through the light guide plate, while being diffused, to be emitted from one surface of the light guide plate through the optical sheet, for irradiating the liquid crystal panel.
In recent years, as the bezel of a display apparatus is being slimmed, the display apparatus configured as described above is making the interval closer between the inner edges of the frame body covering the edges of the light guide plate and the display area of the screen of the liquid crystal panel. Because the frame body hinders light transmission, shadows of the frame body is formed at the edge part of the display area, which makes the edge part dark. The problem here is that the display quality of an image is deteriorated in this way.
Japanese Patent Application Laid-open No. 2012-164507 suggests a display apparatus and a backlight device used in the display apparatus, for the solution of the problem described above. The display apparatus described in Patent Document 1 has a positioning hole formed in an optical sheet covering the light emitting surface of the light guide plate and a positioning pin formed in the light guide plate for insertion into the positioning hole. The optical sheet is arranged on the light guide plate and positioned by the insertion of the positioning pin into the positioning hole.
Because the optical sheet is placed directly on the light guide plate, the frame body does not have to include the positioning function for the optical sheet, which enables the frame to be slimmed and thus avoids the dark part.